Flow control apparatus



Feb. 13, 1968 WELLS FLOW CONTROL APPARATUS Filed NOV. 19, 1964 O .T s 4 W m 2 M m m l 2 R m m 6 O 3 0 m .1 .n /m w m n 7 7g mm ,W\\\ 4% 22/ M L m a x F ATTIORNEYS United States Patent 3,368,587 FLOW CONTROL APPARATUS Arthur N. Wells, Belmont, Califi, assignor to Apparatus Controls, San Carlos, Calif., a corporation of California Filed-Nov. 19, 1964, Ser. No. 412,374 13 Claims. (Cl. 138-44) The present invention relates to new and novel flow control apparatus, and more particularly to fluid flow control apparatus which is especially adapted for use as a choke in oil Wells.

While the present invention is especially adapted for use as a bottom-hole choke in oil Wells, the apparatus may also be used for controlling the flow of other fluids and liquids of mixed character.

A special problem encountered in the operation of oil wells is the fact that the fluids passing upwardly to the surface may contain gas, oil and salt water. Each of these particular substances exhibits a different friction to flowing so that normally the gas moves most rapidly, the oil less rapidly, and the water even less rapidly.

Since it is desirable to conserve the gas in the formation while extracting the oil, it is customary to restrict or slow down the fluid movement so that the oil and Water can travel upwardly from the Well in proper proportion to the flow of gas. The primary purpose of such chokes as used in oil wells is accordingly to reduce the general flow rate so that the liquids may flow at the same general speed as the gas.

Oil Well chokes are generally placed at some critically convenient depth in the oil well. Conventional chokes are generally of three known types. Firstly, a tubing section having a long hole of restricted small diameter employed for introducing resistance to flow by friction. Secondly, a hanger insert fitting lowered by wire line into the well tubing is set in place, such insert having a long small diameter hole for the purpose of providing the necessary friction to restrain movement of the fluid therethrough. Thirdly, an adjustable orifice tubing fitting may be provided, this adjustable fitting being regulated by rotation of the tubing to provide an adjustable choke.

The principal problem and main disadvantage of prior art chokes is that they are rarely in correct adjustment with the ever-changing conditions of the fluid mixtures flowing therethrough. Accordingly, oil well chokes do not always serve their true purpose of providing a smooth,-

eflicient flow without surging or separating the various components of the fluid mixture. For example, if the choke is too open, or in other words, does not provide suflicient restriction, the gas rushes to the surface, and virtually dries out the fluids to form cakes and coatings in the tubing. On the other hand, if the choke is closed too much, or, in other words, if there is too much restriction, then the liquid is so dense that it requires extra pumping to lift it out of the well.

The arrangement of the present invention provides a novel construction wherein a nozzle portion is provided, this nozzle portion extending at least partly into avcavity provided in a tubular body means. The nozzle portion has a tapered entry portion, an intermediate throat portion and a final chamber portion which opens into the cavity within the tubular body means. Longitudinal extensions are provided on the nozzle portion extending longitudinally into the cavity of the tubular body means for guiding the fluid mixture out of the nozzle portion. The nozzle portion also includes laterally extending holes providing communication between the cavity and the chamber portion of the nozzle portion.

The various dimensions and interrelationships of the parts of the nozzle portion are of a critical nature, and it is these particular interrelated proportions which aiford the new and improved smooth and eflicient flow without surging or separating of the various fluids which is a particular objective of the invent-ion.

The fluid mixture leaving the nozzle portion expands rapidly in the enlarged space of the cavity within the tubular body means to create turbulence in this area, part of the mixed fluid moving outwardly away from the nozzle portion and thence through an associated conduit means, while another part of the mixed fluid expands out of the chamber portion and recirculates back through the holes provided in the nozzle portion to enter again into the chamber portion of the nozzle portion.

Any liquid that tends to separate out of the fluid mixture within the cavity will generally run down along the wall of the tubular body means and be recirculated through the holes extending laterally of the nozzle portion.

It is accordingly apparent that the flow control choke of the present invention restricts fluid flow through the nozzle portion by fluid back pressure which is recirculated through the laterally extending holes into the chamber portion. This is in contrast to the prior art wherein restriction is accomplished solely by means of providing a narrow passage so as to produce sufficient friction to retard fluid flow. Accordingly, wear of the apparatus is substantially reduced in the present invention wherein abrasive matter is carried by the fluids since the orifice means or throat portion of the nozzle portion may be considerably larger than the orifice provided in the prior art wherein friction is relied upon to slow down the fluid flow.

It will be apparent that fluid which is recirculated inwardly through the laterally extending holes in the nozzle portion will partially obstruct the flow through the choke orifice to thereby reduce the general flow rate of the fluid mixture.

If the arrangement of the present invention is employed with an oil bearing formation wherein the pressure is suflicient to drive both gas and liquids to the surface, a condition commonly known as a flowing well, the restriction provided by the choke of the present invention being of greater diameter than ordinary chokes, would appear to be insufficient. However, since the condition of excess gas in the flowing fluid tends to cause the separated liquids to collect on the walls of the cavity, these liquids will run down along the walls of the cavity and be recirculated through the laterally extending holes in the nozzle portion to obstruct and add weight to the fluid stream passing through the throat portion or orifice of the nozzle portion. The liquid obstruction will thereby produce a back pressure and choke down the gas flow such that proper operation is obtained.

If the diameter of the orifice of the choke according to the present invention coincides with the orifice diameter of prior art chokes, the present choke will perform equally well. In this instance, the restriction is just right for gaining an optimum gas-oil ratio and optimum propulsion of the fluid mixture up through the well tubing to the surface. When this condition prevails, the liquids are moving upwardly in a proper manner and very little gas-oil mixture returns for recirculation through the lateral holes in the nozzle portion. Since the quality of the recirculated fluid is the same as that of the fluid passing through the orifice part of the nozzle portion, absolutely no change occurs in the fluid flow.

To further illustrate the manner in which the present invention operates, let us assume that the orifice or throat diameter of the choke of the present invention is smaller than that which would be employed with prior art chokes. If an ordinary choke having such a diameter were employed, there would be a tendency for stoppage of the flow because there is insuflicient gas propulsion eflect to carry the liquid column upwardly. Later, some gas would enter the liquid column and the top of the liquid column would become charged with gas and flow off in a surge which would then again stop. The surging is actually caused by a slight insufficiency of gas, and then the liquid rises to the surface and falls back again. In the meantime, considerable gas will escape upwardly at low pressure without giving assistance to the lifting of the liquids. On the other hand, with the arrangement of the present invention, a suflicient amount of gas is recirculated through the lateral holes in the nozzle portion into the nozzle chamber portion so that the gas becomes intimately mixed with the liquid in extremely minute globules. This provides a mixture of relatively low density and quite stable enough to provide a low-density column suitable for assuring a more constant upward flow of the fluid mixture.

It is accordingly apparent that the flow control apparatus of the present invention provides satisfactory results over a wide range of operating conditions without seriously impairing the efficiency of oil production.

The flow control apparatus of the present invention provides satisfactory gas, oil and water mixtures with greater certainty for the maintenance of continuous fluid flow without either caking or surging.

A flowing well may also be successfully operated by utilizing the choke of the present invention of slightly oversized dimension and providing a surface valve for restricting fluid movement at the surface. The surface valve should be slightly shut in so as to slow down the flow enough to permit time for liquid recirculation to restrict gas at the choke. If the fluid flow stops because of restriction, then the valve should be opened slightly to permit faster gas entry through the orifice of the choke.

The flow control apparatus choke of the present invention may also be installed in the gas anchor to a pumping 'well. Since small amounts of gas can be caused to be intimately entrained with the liquid, the problem of gaslocking of pumps may be avoided. In addition, some pumping costs can be saved by providing an additional.

measure of flowing property to the fluid thereby permitting the pump to function with less lifting force.

The apparatus of the present invention may also be employed in oil production operations Where there is vertually no gas, but only oil and salt water. The salt water is heavier than oil and therefore is more likely to be recirculated through the nozzle portion. This condition adds weight at the orifice or throat outlet thereby retarding some oil flow. The flow of the salt water then is increased slightly proportionately, thereby removing more than the usual amount of salt water from the (formation. This removal of salt water which usually lags behind in the formation, tends to maintain the porosity of the information insofar as oil movement is concerned. In this instance, the choke should be installed in the tubing or in the gas anchor below the pump.

The flow control apparatus of the present invention can also function as a ultrasonic whistle under periodic flow conditions thereby maintaining a well-mixed fluid in the conduit means. Accordingly, the present invention can be employed other than in oil wells for circulating other liquids that need to be homogenized.

An object of the present invention is to provide new and improved fluid flow control apparatus which is especially adapted for use as a choke in oil wells.

Another object of the invention is the provision of fluid flow control apparatus which reduces the general flow rate of a fluid mixture to allow the liquid and gas of the mixture to flow at similar rates.

A further object of the invention is to provide fluid flow control apparatus which provides smooth eflicient flow without surging or separating of the various components of the fluid mixture.

Yet another object of the invention is the provision of fluid flow control apparatus which provides optimum fluid mixture regulation over a wide range of operating con ditions.

Still another object of the invention is to provide fluid flow control apparatus which reduces wear particularly when abrasive matter is carried by the fluid mixture.

Yet a further object of the invention is the provision of fluid flow apparatus which functions as an ultrasonic whistle for homogenizing fluid mixtures flowing therethrough.

Other objects and many attendant advantages of the invention will become more apparent when considered in connection with the specification and accompanying drawings, wherein:

FIG. 1 is a longitudinal section through fluid flow control apparatus according to the present invention;

FIG. 2 is a sectional view taken substantially along the line 22 of FIG. 1 looking in the direction of the arrows;

FIG. 3 is a sectional view taken substantially along line 3-3 of FIG. 1 looking in the direction of the arrows; and

FIG. 4 is a top perspective view partly broken away illustrating the details of construction of the nozzle portion of the apparatus.

Materials used in the fluid flow control apparatus of the present invention are usually of steel, but, however, brass or bronze may be equally acceptable in certain instances. In general, it is considered preferable that the outer tubular body means be for-med of stainless steel or the like while the nozzle portion should be of a salt water resistant stainless steel alloy which is processed so as to have a surface in contact with the flowing fluid which is hard and of a slippery non-sticking quality. Some bronzes may also be adapted for retaining an oil film. The surfaces of the nozzle portion may be treated in a manner similar to the modern non-stick frying pans, this slippery type of surface being advantageous in preventing clogging of the apparatus.

Referring now to the drawings, wherein like reference characters designate corresponding parts throughout the several views, a tubular body means 10 is provided having a central cavity 12 formed therein, cavity 12 being of substantially cylindrical configuration and extending from a shoulder portion 13 upwardly of the upper end of the body means, cavity 12 having the length which is at least approximately three times the diameter thereof. A body means is provided with a threaded opening 14 at the upper end thereof as seen in FIG. 1, this threaded opening receiving the lower threaded end 16 of a con duit means 18. This conduit means represents the outlet conduit from the apparatus, the fluid flow being in an upward direction as indicated by arrow F in FIG. 1. It will be understood that the apparatus as illustrated will normally operate in the vertical position wherein the fluid flow is vertically upwardly through the apparatus from an oil bearing formation to the surface.

The lower end of tubular body means 10 is provided with a threaded opening 20 which receives the threaded outer surface of a bushing 22. Bushing 22 is provided with a bore formed therethrough the lower portion of which is threaded as indicated at 24, this threaded portion receiving the upper threaded end portion 26 of a conduit means 28 which represents the inlet conduit to the apparatus of the present invention.

Body means 10 is also provided with an annular inwardly extending portion 30 the upper surface of which provides the shoulder 13 as described previously. Portion 30 is provided with a central threaded opening 31 formed therethrough, and a nozzle portion indicated generally by reference numeral 32 is provided with a lower threaded portion 34 as seen particularly in FIG. 4 which is adapted to be threaded within opening 21 for mounting the nozzle portion in operative position at an intermediate point within the body means 10. Nozzle portion 32 may be installed or removed relative to body means 10 by employing a long shank spanner which is adapted to engage with the extensions formed on the nozzle portion as hereinafter described.

The size of the cavity or bore formed within the body means may be substantially the same as that of the conduit means with which it is connected, and it will be particularly noted that the cross sectional area of the cavity 12 is substantially greater than that of the discharge portion of the nozzle portion which extends into the cavity so that the fluid mixture discharging from the nozzle portion is adapted to expand within cavity portion 12 and to produce turbulence in this area.

The nozzle portion is provided with an axial bore extending therethrough. This axial bore includes an entry portion 40 which is of substantially frusto-conical configuration and which has a slope of approximately 45 degrees to a vertical line extending through the longitudinal axis of the apparatus as seen in FIG. 1. The entry portion 40 joins with a throat or orifice portion 42 of substantially uniform diameter and the length of which is at least equal to the diameter thereof.

The discharge from the throat portion 42 is connected by means of a chamfered portion 44 with a chamber portion 46 which opens longitudinally into the cavity 12 provided in the body means. The chamber portion has a substantially uniform diameter throughout which is greater than the diameter of the throat portion 42 such that the cross sectional area of the chamber portion is approximately twice the cross sectional area of the throat portion 42. The length of the chamber portion 46 from the discharge end of the throat portion to th end 48 of the chamber portion is approximately twice the diameter of the throat portion 42.

A pair of diametrically opposite extensions 50 and 52 extend longitudinally from the end of the chamber portion into the cavity 12. These extensions are each of generally arcuate cross sectional configuration as seen in FIG. 2, each of the extensions having a width from side to side thereof which is substantially equal to the diameter of the throat portion 42, the extensions each having a length extending in the longitudinal direction of the apparatus which is substantially equal to the width of the extensions.

The nozzle portion is also provided with a pair of diametrically opposite laterally extending holes 60 and 62. As seen in FIG. 1, it will be noted that an annular space .66 is provided between the outer surface of that portion of the nozzle portion which extends into cavity 12 and the wall of the body means 10. The holes 60 and 62 provide communication between annular space 66 and the interior of the chamber portion 46 previously described. It is accordingly apparent that holes 60 and 62 provide a recirculation path whereby any substance which drops down along the surface of cavity 12 may be directed inwardly into chamber 46 and recirculateed back up into the cavity 12 by the flow of fluid discharging from the throat portion 42.

It will be noted that the holes are spaced from the discharge portion of the throat portion a very small distance such that they are closely adjacent thereto, the diameter of each of holes 60 and 62 being substantially the same as the diameter of throat portion 42.

The width of the annular space 66, or in other words, the radial distance from the outer surface of the nozzle portion to the inner surface of the body means should be at least as great as approximately the diameter of holes 60 and 62 in order to avoid the effects of capillary action and surface tension phenomena. It is also important to note that the cross sectional area of the chamber portion 46 is substantially twice the cross sectional area of the throat portion 42 so as to enable the amount of fluid recirculated through holes 60 and 62 into the chamber portion 46 to be substantially the same as the incoming fluid discharging from the throat portion 42 to gain optimum emulsion-free mixing of fluids.

Fluid rising through conduit 28 is channeled by'the inlet entry portion 40 into the orifice or throat portion 42 and then proceeds through the chamber portion 46 at a high velocity. It is important to note that the throat or orifice portion 42 is relatively short and friction is held to a minimum in contrast to conventional chokes wherein a long orifice of small diameter is provided so as to introduce friction. Since the diameter of chamber portion 46 is not much greater than the diameter of the throat portion, there is a tendency to sweep the chamber to provide a partial suction which draws fluid through holes 60 and 62 as the high velocity fluid passes through the chamber portioin.

The fluid discharge from chamer portion 46 is therefore a mixture of the fluid flow passing through the throat portion 42 and the recirculated fluid entering through holes 60 and 62. A part of the mixed fluid moves rapidly upwardly, guided by extensions 50 and 52 while another part of the fluid mixture discharged from the chamber portion 46 expands over the upper surfaces 48 of the chamber portion from whence it may either continue upwardly or may be drawn downwardly into the annular space 66.

It is apparent that the choke of the present invention may be constructed so as to fit conduit means of various sizes, and furthermore the nozzle portion is an insert which may be readily moved and replaced as desired. Thus, the nozzle portion may be replaced by another nozzle portion having an orifice and chamber portion of different dimensions as well as the extensions and holes which also may be varied in size. However, it is important that the relative dimensions of these various components be maintained within the critical ranges as set forth hereinabove so as to produce proper operation of the apparatus.

It is apparent from the foregoing that there is provided according to the present invention new and novel fluid flow control apparatus which is especially adapted for use as a choke in oil wells. The arrangement of the present invention reduces the general flow rate of the fluid mixture passing thereth'rough so as to allow the liquid to catch up with the gas and provides smooth efiicient flow without surging or separating the various components of the fluid mixture. The present invention provides optimum fluid mixture regulation over a wide range of operating conditions and reduces wear when abrasive matter is carried by the'fluid mixture. Additionally, the apparatus operates as an ultrasonic whistle so as to produce homogenization of the fluid mixture.

As this invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, and since the scope of the'invention is defined by the appended claims, all changes that fall within the metes and bounds of the claims or that form their functional as well as coinjointly cooperative equivalents are therefore intended to be embraced by those claims.

I claim:

1. Flow control apparatus comprising elongated tubular laterally imperforate body means adapted to be connected to fluid flow conduit means, said body means having a central cavity formed therewithin, a nozzle portion supported by said body means and extending at least partly into said cavity to define an annular space between said nozzle portion and said body means, said nozzle portion having an axial bore formed therethrough, said bore including a tapered entry portion, an elongated axially extending intermediate thro'at portion of substantially uniform diameter in communication with said entry portion, and an elongated axially extending chamber portion of substantially uniform diameter in communication with said throat portion, said chamber portion opening into said central cavity, said chamber portion having a greater cross sectional area than said throat portion, said nozzle portion having a plurality of holes formed therein and providing communication between said chamber portion and said annular space.

2.. Apparatus as defined in claim 1 wherein the cross sectional area of said chamber portion is substantially twice the cross sectional area of said throat portion.

3. Apparatus as defined in claim 1 wherein the diameter of each of said holes formed in said nozzle portion is substantially the same as the diameter of said throat portion.

4. Flow control apparatus comprising an elongated tubular body means having a central cavity formed there- Within, a nozzle portion supported by said body means and extending at least partly into said cavity and defining an annular space between said nozzle portion and said body means, said nozzle portion having an axial bore extending therethrough, said axial bore including a tapered entry portion, an elongated axially extending intermediate throat portion of substantially uniform diameter in communication with said entry portion, and an elongated axially extending chamber portion of substantially uniform diameter and disposed in communication with said throat portion, said chamber portion opening into said cavity, said nozzle portion including extension means extending longitudinally from the end of said chamber portion and extending into said cavity, the diameter of said chamber portion being greater than the diameter of said throat portion, the cross sectional area of said cavity being substantially greater than the cross sectional area of said chamber portion, said nozzle portion having a plurality of holes extending laterally therethrough to provide communication between said chamber portion and said annular space, the length of said central cavity being substantially greater than the diameter thereof.

5. Apparatus as defined in claim 4 wherein the length of said central cavity is at least approximately three times the diameter of said central cavity.

6. Apparatus as defined in claim 4 wherein the length of said throat portion is at least as great as the diameter of said throat portion.

7. Apparatus as defined in claim 4 wherein the cross sectional area of said chamber portion is approximately twice the cross sectional area of said throat portion.

-8. Apparatus as defined in claim 7 wherein the length of said chamber portion is approximately twice the diameter of said throat portion.

9. Apparatus as defined in claim 4 wherein said holes formed in said nozzle portion are positioned closely adjacent the point where said throat portions joins said chamber portion, each of said holes having a diameter substantially the same as the diameter of said throat portion.

10. Apparatus as defined in claim 4 wherein each of said extensions has a width equal substantially to the diameter of said throat portion, and wherein the length 8 of each of said extensions is substantially the same as the width thereof.

11. Apparatus as defined in claim 4 wherein said annular space has a width at least as great as approximately the diameter of said holes.

12. Flow control apparatus comprising elongated tubular body means adapted to be connected to fluid flow conduit means, said body means having a centrally substantially cylindrical cavity therewithin, said cavity having a length at least approximately three times the diameter of said cavity, a nozzle portion supported by said body means and extending at least partly into said cavity to define an annular space between said nozzle portion and said body means, said nozzle portion having an axial bore extending therethrough, said axial bore including a substantially conical entry portion, an elongated axially extending intermediate throat portion of substantially uniform diameter, the length of said throat portion being at least as great as the diameter of said throat portion, said 'axial bore including an elongated axially extending chamber portion disposed downstream of said throat portion and in communication therewith, said throat portion being in communication with said entry portion, said chamber portion having a diameter greater than that of said throat portion and having a cross sectional area which is approximately twice the cross sectional area of said throat portion, the length of said chamber portion being approximately twice the diameter of said throat portion, said nozzle portion including a pair of diametrically opposite laterally extending holes providing communication between said chamber portion and said annular space, said holes being positioned closely adjacent the point where said chamber portion joins with said throat portion, said nozzle portion including a pair of diametrically opposite extensions extending longitudinally downstream of said chamber portion, each of said extensions having a Width and a length which is substantially equal, the width and length of each of said extensions being approximately the same as the diameter of said throat portion, said annular space having a width at least approximately as great as the diameter of said holes.

13. Apparatus as defined in claim 12 wherein the cross sectional area of said cavity within said body means is substantially greater than the cross sectional area of said chamber portion to permit expansion of fluids discharging from said chamber portion into said cavity and to provide turbulence of such fluids.

References Cited UNITED .STATES PATENTS 2,118,428 5/1938 Chrisman 138-40 X 2,797,755 7/1957 Bobo 166--99 X LAVERNE D. GEIGER, Primary Examiner.

BRADFORD KILE, Assistant Examiner. 

1. FLOW CONTROL APPARATUS COMPRISING ELONGATED TUBULAR LATERALLY IMPERFORATE BODY MEANS ADAPTED TO BE CONNECTED TO FLUID FLOW CONDUIT MEANS, SAID BODY MEANS HAVING A CENTRAL CAVITY FORMED THEREWITHIN, A NOZZLE PORTION SUPPORTED BY SAID BODY MEANS AND EXTENDING AT LEAST PARTLY INTO SAID CAVITY TO DEFINE AN ANNULAR SPACE BETWEEN SAID NOZZLE PORTION AND SAID BODY MEANS, SAID NOZZLE PORTION HAVING AN AXIAL BORE FORMED THERETHROUGH, SAID BORE INCLUDING A TAPERED ENTRY PORTION, AN ELONGATED AXIALLY EXTENDING INTERMEDIATE THROAT PORTION OF SUBSTANTIALLY UNIFORM DIAMETER IN COMMUNICATION WITH SAID ENTRY PORTION, AND AN ELONGATED AXIALLY EXTENDING CHAMBER PORTION OF SUBSTANTIALLY UNIFORM DIAMETER IN COMMUNICATION WITH SAID THROAT PORTION, SAID CHAMBER PORTION OPENING INTO SAID CENTRAL CAVITY, SAID CHAMBER PORTION HAVING A GREATER CROSS SECTIONAL AREA THAN SAID THROAT PORTION, SAID NOZZLE 